Mixed-signal integrated circuits typically include radio frequency (RF) receivers and/or transmitters as well as digital subsystems. Often radio frequency receivers and/or transmitters digitize small-signal analog time domain waveforms for use in digital subsystems of the mixed-signal integrated circuit. However, high-speed processor clocks and internal digital communications of the digital subsystems may generate digital switching noise that interferes with the digitization of the small-signal analog signals. Additionally, stray capacitances intrinsic to some of the materials used during the integrated circuit fabrication process may also generate noise that interferes with the digitization of the small-signal analog signals. Some radio frequency receivers may also be sensitive to noise from power components of the mixed-signal integrated circuits.
Noise and other electromagnetic interference may bias analog samples of small-signal waveforms and, therefore, degrade the signal-to-noise ratio of the radio frequency receivers and/or transmitters. The noise and other electromagnetic interference may also degrade mask compliance of the radio frequency transmitter and may increase the bit error rate. Mask compliance generally reduces adjacent-channel interference by limiting transmissions at frequencies outside a particular bandwidth.
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The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.